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THE CANADIAN NATURALIST. 



[Jan. 



fossil. The most marked peculiarity was in the structure of the 

 jaws and teeth, both as regards the form and texture. The form 

 of the jaws will be best understood by the following figures. 



Fig. 1 . 



Lower Jaw — one-eighth natural size. 

 Figr. 2. 



Front view of Head — one-eighth natural size. 



The head terminated anteriorly and above in two great incisors, 

 representing the premaxillary, behind which on either side were 

 the maxillaries — broad, flattened bones of very dense tissue — along 

 the lower edge of which was set one row of small robust teeth, 

 which were neither implanted in sockets nor cemented to the 

 jaw, but were formed by the consolidation and prolongation of the 

 jaw tissue. The mandibles are over two feet long by six inches 

 deep, laterally flattened and very massive, being without any 

 medullary cavity. The anterior extremity was turned up in a 

 huge triangular tooth, composed of dense ivory-like tissue, which 



